The present invention relates to an ink jet recording method which forms characters and/or images by means of ejecting ink droplets onto the recording medium, an ink jet recording apparatus, and printed products, in particular, an ink jet recording technology by which dye or color material in the ink on the recording medium is rendered insoluble or is caused to aggregate.
The ink jet recording method is widely used in printers, copying machines, facsimiles, and the like because of its advantages such as low noise, low running cost, ease of size reduction, ease of colorization, and the like.
In order to produce water resistant, nonbleeding color images with highly developed color sing a conventional ink jet recording, it is necessary to use a dedicated paper which comprises a water resistant ink absorbing layer. In recent years, due to improvement in the ink, reasonably practical printing methods usable with plain paper have been developed, which is used with the printers, copying machines, or the like by a large quantity. However, the quality of the print produced on the plain paper still remains at an unsatisfactory level.
As for methods for improving the water resistant property or the water resistance of the images by means of improving the ink, one of the known methods is to give water resistance to the color material within the ink. Basically, the ink used with this method is rendered hard to re-dissolve in the water once it dries. Therefore, it suffers from the problem that it is liable to clog the recording head nozzles. It is not impossible to prevent this problem, but the prevention itself creates another problem in that the apparatus structure becomes rather complicated.
A Japanese Laid-Open Patent Application No. 84,992/1981 discloses a method in which the recording medium is coated in advance with material capable of fixing the dye. However, this method requires the use of a dedicated recording medium, and also, in order to coat the dye fixing material, the apparatus size becomes large, making cost increase inevitable. In addition, it is rather difficult to coat the recording medium with the material capable of fixing the dye stably, by a predetermined thickness.
Further, another Japanese Laid-Open Patent Application No. 63,185/1989 discloses an art for adhering colorless ink, which is capable of rendering the dye insoluble, onto the recording medium with the use of an ink jet recording head. According to this method, the dot diameter of the colorless ink is set to be larger than that of the real ink, therefore, the desired properties can be satisfactorily obtained even when the landing or shot spots for the image producing ink and colorless ink are slightly deviated from each other. However, this method shoots the colorless ink over the entire region upon which the images are formed; therefore, it suffers from the problem that the consumption of the colorless ink becomes large, inviting thereby the cost increase. Also, since a larger amount of the ink than usual is injected into the recording medium, a further problem is created in that it takes a longer time for the ink to dry, and the landing points of the ink are liable to be displaced due to the recording material cockling which occurs as the ink adhered to the recording medium and dries there. In particular, when the color images are formed, there is a problem that this landing point displacement caused by the cockling leads to color irregularity, which greatly deteriorates the image quality.
Another ink jet recording method, in which desired images are recorded by ejecting the ink from nozzles onto the recording medium with the function of pressure, electrical voltage, or the like, is recorded in U.S. Pat. No. 4,538,160, which is characterized in that the desired images are recorded twice in an overlaying manner, first with the actual recording ink and then, with processing ink capable of improving the picture quality, preservability, spreadability, and the like.
As for the structure of a recording apparatus to be used to carry out this recording method, signals supplied from an image signal control circuit for ejecting the inks of different color, that is, yellow, magenta, cyan, and black, are also supplied to a delay circuit through an OR circuit at the same time, being thereby supplied to a head which ejects the processing ink. However, according to this invention, the processing ink is ejected over the entire surface of the recorded desired image, that is, the entire surface on which the recording ink is ejected; therefore, the consumption of the processing ink is large. In other words, a large amount of the processing ink adheres to the recording medium; therefore, the recording medium is liable to suffer from cockling.
The present invention was made in consideration of the above mentioned problems, and its primary object is to provide an ink jet recording method, an ink jet recording apparatus, and print products, which can give to recorded images better water resistance than the conventional method even when plain paper is used; which makes it difficult for feathering (ink bleeding in the direction of the fiber in the recording medium) to occur; which produces high density images; which in the case of color recording, prevents inter-color bleeding, producing thereby high quality images; which reduces the consumption of the recording properties improving liquid, economizing thereby the recording.
Another object of the present invention is to provide a recording method comprising steps of:
ejecting the ink onto the recording medium on the basis of image data; and
ejecting the recording properties improving liquid onto the recording medium so that the recording properties of the ink to be ejected onto the recording medium s improved;
wherein one of said steps of ejecting ink and ejecting the recording properties improving liquid is carried out ahead of the other, which is carried out thereafter; and
during the step in which the recording properties improving liquid is ejected, said recording properties improving liquid is discriminately ejected onto the recording medium surface onto which the ink is to be ejected, so that some portions thereof are exposed to the liquid and the others are not.
Another object of the present invention is to provide a recording apparatus employing a head for ejecting the ink onto the recording medium, on the basis of the image data, and a head for ejecting the recording properties improving liquid onto the recording medium so as to improve the recording properties of the ink ejected onto the recording medium, comprising:
ejection point data establishing means for establishing the ejection point data on the basis of the image data, so that the recording properties improving liquid is discriminately ejected onto the recording medium surface onto which the ink is to be ejected, in such a manner that some portions of the recording medium surface are covered with the recording properties improving liquid and the others are not; and
driving signal supplying means for supplying driving signals to the head for recording properties improving liquid, on the basis of the ejection point data established by the ejection point data establishing means.
Another object of the present invention is to provide printed products comprising:
recording medium; and
an image area formed on said recording medium with the ink;
wherein said image area comprises portions where the ink coexists with the ingredients for improving the recording properties of the ink on the recording medium, and portions where the ink exists without the presence of such ingredients.
According to an aspect of the present invention, it is conceivable that there are the following ink combinations; black ink alone; yellow, magenta, cyan, and black inks; yellow, magenta and cyan inks; and also, these color inks and other specific color ink or color inks, wherein the ejection data for the recording properties improving liquid is established on the basis of the ejection data for these inks that is, the image data.
According to another aspect of the present invention, it is possible to eject only a minimum necessary amount of the recording properties improving liquid; therefore, the water resistance of the images on the plain paper can be improved without deteriorating the image quality.
According to an aspect of the ink jet printing method of the present invention, color inks containing color material, and colorless or virtually colorless recording properties improving liquid containing ingredients for rendering the ink ingredients insoluble or aggregating them, are ejected onto the recording medium, wherein the ink and recording properties improving liquid mix and/or react to each other to give the recorded images the water resistance so that reliable high quality images can be obtained.
In this embodiment, improving the print properties includes: improving image quality such as density, saturation, degree of edge sharpness, dot diameter, and the like; improving the fixity of the ink; and improving the preservability of the image, that is, the environment resistance such as the water resistance or light resistance. The print properties improving liquid includes: liquid capable of rendering insoluble the dyes within the ink; liquid capable of destroying pigment dispersion; liquid for improving the print properties; and the like. The terminology xe2x80x9crendering insolublexe2x80x9d refers to a phenomenon that an anionic radical contained within the ink and a cationic radical of the cationic substance contained within the print properties improving liquid react to each other, being thereby ionicly bonded, whereby the dye having been uniformly dissolved within the ink separates from the solution. It should be noted here that such effects of the present invention as the suppression of color bleeding and the improvement in color development, character quality, and fixity can be obtained even when not all of the dye in the ink is rendered insoluble. As for the terminology xe2x80x9caggregation or coagulationxe2x80x9d it is used in the same meaning as. xe2x80x9crendering or making insolublexe2x80x9d when the coloring agent in the ink is water soluble dye containing anionic radical, and also, it includes a phenomenon that, when the coloring agent in the ink is pigment, the pigment dispersing agent or pigment surface ionicly reacts with the cationic radical of the cationic substance contained in the print properties improving liquid, destroying pigment dispersion, and subsequently, increasing the pigment diameter. Normally, as the aggregation occurs, ink viscosity increases. It is also to be noted here that such effects of the present invention as the suppression of color bleeding and the improvement in color development, character quality, and fixity can be obtained even when not all of the pigment or pigment dispersing agent within the ink aggregates.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.